1. Field of the Invention
The present invention relates to a temperature measuring apparatus and a temperature measuring method, which can measure a temperature of an object to be measured (for example, a semiconductor wafer or a liquid crystal substrate) in a non-contact manner.
2. Description of the Related Art
Accurately measuring a temperature of a substrate (for example, a semiconductor wafer) to be processed by using a substrate processing apparatus is very important in order to accurately control shapes, properties, and so on of films or holes formed on or in the semiconductor wafer based on a result of various processes such as film formation and etching. Accordingly, a temperature of a semiconductor wafer has been measured by using various conventional methods such as a temperature measuring method using a fluorescent thermometer for measuring a temperature of a rear surface of a base material, a resistance thermometer, or the like.
Recently, a temperature measuring technology using a low-coherence interferometer which can directly measure a temperature of a semiconductor wafer, which is difficult to do with the conventional temperature measuring methods, has been developed. Also, as the temperature measuring technology using the low-coherence interferometer, a technology has been suggested in which a light from a light source is divided into a measurement light for temperature measurement and a reference light by a first splitter, the measurement light is divided into n measurement lights by a second splitter, the n measurement lights are emitted to n measurement points, and interference between reflected lights of the n measurement lights and a reflected light of the reference light reflected by a reference light reflecting unit is measured to simultaneously measure temperatures of the plurality of (n) measurement points (refer to, for example, Patent Document 1).
However, in the above conventional technology, since a number of measurement points are limited by a number of lights obtained by the second splitter, it is difficult to measure temperatures of more measurement points as needed.    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2006-112826